The overall purpose of this study is to investigate the effects of prenatal exposure to ethanol on the development of the central nervous system using the hippocampus of the rat as a model system. Utilizing a multidisciplinary approach, the proposal addresses some of the fundamental questions related to the etiology of the fetal alcohol syndrome: What are the effects of various blood alcohol levels on the development of the hippocampus? Are there critical periods when the hippocampus is most vulnerable to ethanol exposure? Subsequent to prenatal exposure to ethanol, offspring will be screened for structural and functional hippocampal alternations using a variety of techniques including acetylcholinesterase, Timm's, and horseradish peroxidase histochemistiry stains, neurophysiological, and cyclic GMP biochemical analyses. These experiments will provide basic data on the etiology of the fetal alcohol syndrome as well as information that may be useful in establishing guidelines for safe levels of alcohol consumption by pregnant women.